STDs and Adolescents

By Frederick R. Jelovsek, M.D.,

Over a third of all high school students report being sexually active. Of those students, 1/4 will contract a sexually transmitted disease (STD) before graduating high school. This results in 2.5 million teenagers a year who get an STD. Among the STDs most commonly contracted by teens are gonorrhea, chlamydia, HPV, and HIV.  This occurs even with though approximately 50% of teens who are sexually active use condoms.

The traditional method to diagnose STDs such as gonorrhea or chlamydia is to culture discharge from the male urethra or female cervix. In females this requires a pelvic examination which many health care providers do not feel comfortable doing. Teens don't feel comfortable having a pelvic done either. Cultures have recently been replaced by DNA amplification techniques which have been shown to be cost-effective, sensitive and specific in symptomatic men and women. The most difficult task is to identify those 80% of women who are asymptomatic but still infected with either chlamydia or gonorrhea without subjecting them all to a pelvic exam.

Krowchuk has reviewed new diagnostic techniques and strategies in Krowchuk, DP:Sexually transmitted diseases in adolescents: What's new? Southern Med J 1998; 91(2):124- 131. In order to avoid invasive testing, a screening test has been used in which the first 10-15 ml (1/2 oz) of voided urine (FVU) is tested by the dipstick method looking for leukocyte esterase. If this test is negative, its fairly certain (83-96%) that there is NOT an infection. If its positive, we don't know for sure but further testing of that FVU by the DNA methods can be done. In one study*, using ligase chain reaction on FVU specimens in women, they found a sensitivity of 94% in picking up almost all the cases in which a gonorrhea infection was present.

This makes the best diagnostic strategy for screening as follows:

• Collect first 10-15 ml of urine
• Perform urinary dip for leukocyte esterase (inexpensive) -- if negative, no further testing.
• Use DNA techniques (ligase chain reaction, polymerase chain reaction) on the urine specimen. A positive reaction is reason to treat.

This screening strategy should pick up 90% of women with chlamydia or gonorrhea infections. If you suspect a possible infection, screening a first void urine with a leukocyte estrase dip would tell you if you should go to the medical office for further testing.

* - Smith KR, Ching S, Lee H et al: Evaluation of ligase chain reaction for use with urine for identification of Neisseria gonorrhoeae in females attending a sexually transmitted disease clinic. J Clin Microbiol 1995; 33:455-457.